Daric Barton had a good look at a ball while hitting in the batting cage. The Oakland Athletics held their second workout of the spring mostly for pitchers and catchers Thursday February 17, 2011 at Phoenix Stadium.

Photo: Brant Ward, The Chronicle

Daric Barton had a good look at a ball while hitting in the batting...

Barton came into spring camp with a new physique. The A's first baseman believes he has added about 15 pounds of muscle while losing 10 pounds of fat, based on his body fat decrease - he's down 4 percent after strenuous workouts this offseason with Southern California trainer Brad Davidson. Barton cut out carbohydrates for two weeks, and he's trying to stick to a protein-rich diet.

His teammates have noticed the difference. "He was a fatty," A's starter Dallas Braden said. "A little baby polar bear, that's what I called him. It's encouraging to know he's got himself on the right track."

Barton already can tell the extra muscle will help him at the plate.

"I've never felt so good swinging the bat," Barton said. "I knew right away things would be better, taking batting practice. I would say I have more pop."

More pop is precisely what the A's need, of course, after finishing second to last in the league in home runs. And the one knock on Barton in his young career is that he hasn't provided enough power playing a position that typically features it.

The A's, of course, love what Barton does bring, even without large homer totals. He led the league in walks last year, and his defensive work is outstanding.

"I don't think you can put a value on it," Braden said. "I called him when he didn't get the Gold Glove and I was like, 'Oh, my God, are you serious?' But with Daric, day in and day out, you see him get to balls no one else possibly could get to. It's a crying shame no one has acknowledged that."

"Whenever I hear people talking about our need for an upgrade at first base, I chuckle," A's general manager Billy Beane said. "We're perfectly happy and very pleased - his defense in our opinion is amongst the best at the position in the game, his on-base percentage is good and both are getting better. ... He's a championship-caliber first baseman."

Beane noted that despite some injuries, Barton played in 159 games last year.

Why is Barton working with a trainer for the first time in his life? And why now?

"This has nothing to do with the team," he said. "It's more to do with myself. When I went down to Triple-A in '09, everything hit home. I've started to realize more and more that I need to concentrate on my career."

It's all a part of the maturation process that Barton began discussing last year. He came to the A's at the age of 19, with all kinds of talent, and he was happy to just rely on that ability without putting in a lot of extra work.

"He looks great, awesome - a start contrast with where he was a few years ago," Braden said. "This shows how concerned he is about health and preparation, and obviously that spills over to every other facet of the game. As a friend, I'm excited for him.

"He was so young when he got here, a kid with a boatload of expectations, and now he's grown up."